There are many benefits to a decentralized exchange over a traditional exchange. These include:

The ability for anyone to list any asset for trade. There is on governing body that decides what can and cannot be traded.

You control your funds. There is no central body that stores all assets for trade. Instead, each wallet, holds its funds (and each asset issuer holds the real world assets backing the assets it has issued).

Nobody can single-handedly bring down the exchange. Since the exchange is distributed, there is no single-point of failure.

To learn more about the Stellar decentralized exchange and why it is better than traditional exchanges see this dex explainer video